Fudgy and rich peanut butter brownies with a layer of peanut butter filling baked inside and a swirl of it on top. If you're a fan of peanut butter cups, you will love this brownie recipe.
Preheat the oven to 350°F. Cut a piece of parchment paper that is larger than a 9x9" baking pan.
Make the Peanut Butter Filling:
Mix the peanut butter, powdered sugar, vanilla, and milk in a large bowl with a hand mixer. The mixture is ready when it holds together when you press it.
Place the parchment paper in the baking pan. Scoop the peanut butter mixture out of the bowl and place it on the parchment paper. Press the mixture into the pan with your hands so it is in an even layer and filling the pan. Use the parchment paper to lift it out and then set it aside.
Make the Brownie Batter:
Whisk the flour, cocoa powder, and salt in a bowl.
Place the butter and chocolate chips in a microwave-safe bowl. Melt them in the microwave in 30-second increments. Stir between each increment until the chocolate is melted and smooth.
Mix the melted chocolate with both kinds of sugar in a large mixing bowl. It will look a little grainy, which is fine. Add the vanilla, and then add the eggs one at a time, mixing until the batter is smooth after each egg addition.
Gently fold in the dry ingredients to the wet ones until just combined. Be careful not to overmix the batter.
Grease the 9x9 square pan with non-stick cooking spray or line the pan with parchment paper.
Place half of the brownie mixture into the pan and spread it into an even layer.
Cut the formed peanut butter filling into four squares using a small knife. Peel the parchment paper off the peanut butter and place the filling pieces on the batter so the layer covers the brownie batter.
Top the filling with the rest of the brownie batter and spread it into an even layer.
Make the Peanut Butter Swirl Topping
In a small microwave-safe bowl, melt the creamy peanut butter and peanut butter chips in the microwave for approximately 40 seconds. Stir until smooth.
Using a spoon, drop dollops of the topping onto the batter.
To make the swirl design on the surface, use a knife to run lines on the top layer of brownie batter (you do not need to cut down through the peanut butter filling).
Bake the Brownies
Bake the brownies for 35 to 40 minutes or until a toothpick comes out clean.
Cool them in the pan before removing and slicing.
Notes
This recipe works best in a 9x9" baking pan. I've tested it in an 8x8" pan, but I didn't like how thick the brownies ended up.It's optional, but lining the pan with parchment paper makes it easy to lift the baked brownies out of the pan in one piece before slicing them. If you don't use parchment, coat the pan with cooking spray.Even though it's tempting, waiting until the brownies are completely cooled before you slice them is better. If you slice them when warm, you won't get clean slices, and the brownies may not hold together well.If you are not serving them right away, you can wrap the brownies in plastic wrap or store them in an airtight container. They will keep at room temperature for a few days.You can freeze them, too. Wrap the individual brownies in plastic wrap and store them in a large freezer bag or container. They will keep for several months.